1. Field of the Invention
The present invention relates to a wafer holder for a chip inspection apparatus which moves a wafer to inspect a chip thereon in a semiconductor manufacture process, for example.
2. Description of Related Art
There are various known wafer holding devices such as ones used in a chip inspection apparatus which inspects a chip on a wafer while moving the wafer, a wafer inspection apparatus which inspects the surface of a wafer while rotating the wafer, and a semiconductor exposure apparatus which exposes and transfers a circuit pattern onto a photosensitizing agent (photoresist) filmed or coated on the surface of a wafer by irradiating light, for example.
For example, Japanese Laid-open Patent Application Publication No. 2003-324143 discloses such a wafer holder which includes a ring-like wafer receptacle around the circumferential rim of a chuck table to hold a wafer by attaching (fixing) the outer circumferential rim of the wafer onto the wafer receptacle by suction of evacuated air.
In view of preventing the wafer from contaminated or scratched, the wafer needs to avoid contact with other objects as much as possible. For example, during delivery the wafer is placed on a carrier which is configured to support the wafer only at the outer circumferential area thereof. For outer or surface inspection or surface machining of a chip on the wafer, the wafer is held by the above wafer holder when appropriate.
However, there is a problem in the prior art wafer holders that they are configured to hold the wafer on the wafer receptacle by suction so that for placing the wafer on the wafer receptacle, the wafer needs to be separated from the carrier. In the prior art the wafer is transferred from the carrier to the wafer receptacle using tweezers or the like, for example; however, this disadvantageously increases the possibility for the wafer to be made in contact with other objects.